Regenerative sound recording device



arch 1 1 QMEA I B. KWARTIN REGENERATIVE SOUND RECORDING DEV ICE Filed Dec. 26,1950

n u s Patented Mar. 10, 1936 UNITED STATES PATENT OFFICE REGENERATIVE SOUND RECORDING DEVICE 1 Claim.

This invention relates generally to improvements in the art of recording sounds and more particularly to an apparatus for and method of photographically recording such sounds upon a photographic film.

In the production of talking pictures, many serious difficulties have been encountered in the Various attempts to faithfully record and reproduce the sound impressions, one of the chief difficulties being that it has not been possible heretofore to produce a photographic record of sound wherein the nuances between sounds of strongest and weakest character have been clearly and distinctly defined. Not only this, but the sounds as reproduced by these photographic records have not been able to approach the quality of the sounds as originally produced by the instrument or voice, this being largely due to the fact that it has not been possible heretofore to record the very delicate overtones which give quality and character to speech and musical sounds.

Not only has it been difficult, if not entirely impossible, to produce a record wherein the nuances between sounds are clearly and distinctly defined but it also has been exceedingly difficult to take into account in a single record the photographic representations of both the intensity and amplitude differences between the sounds. In all of the systems now more or less generally used for recording sounds, the record of the sounds are dependent either upon the differences in intensity or the differences in amplitude but not upon both, the result being that the recorded sounds are comparatively poor reproductions of the sounds as originally produced by the voice or instrument. While various attempts have been made from time to time to obviate the difficulties hereinbefore mentioned, the results obtained have been far from successful. In those instances where a more or less successful record is obtained of the finest sound effects, the strongest sound effects have not been successfully recorded. On the other hand, where the system was such as to record more faithfully the strongest sound effects it was found that the finest sound effects were unfaithfully recorded. In fact, it has been found almost impossible to successfully and faithfully record in a single record the strongest and finest sound effects without exaggerated amplification in consequence of which these sounds have always been recorded and reproduced in distorted manner.

It is among the objects of the present invention to overcome and obviate the aforementioned and other difficulties by the provision of an apparatus for photographically recording vocal and musical sounds in such manner that the nuances between sounds of strongest and weakest character are larger,'richer, and clearer than have Q been obtainable heretofore;

A further object of this invention is the provision of an apparatus for photographically recording sounds which take into account not only the intensity differences in the photographic representations of the sound, but also the differences in amplitude. In other words, it is an object of the present invention to provide an apparatus which is capable of producing a photographic film sound record both the density and amplitude of which are variable in accordance with variations in intensity of the sounds as originally produced. This is in contradistinction to those photographic film sound records known generally to the art as the variable density and the variable area type.

A still further object of the invention is the provision of a light producing element the light rays produced thereby being variable in accordance with the variations in intensity of the sounds as originally produced, this variable light source being so arranged with respect to a constant source of light as to modulate the effect of the light rays produced by said constant source.

Still another object of the invention is the provision of a pair of lamps, one of which is of constant intensity and the other of which is of variable intensity, said lamps being relatively so arranged with respect to a vibrating mirror as to cause a single beam of light to be directed against a traveling photographic film whereby to produce a record on the latter both the density and amplitude of the sound'record so produced being increased or decreased accordingly as the intensity of the sounds as originally produced are increased or decreased.

Other objects and objects relating to details of construction and assembly of the apparatus as well as to details in the method of using the same will appear more fully hereinafter.

The invention consists substantially in the combination, construction, location and relative arrangement of parts and in the method of using the same, all as will appear more fully hereinafter, as shown in the accompanying drawing, and finally pointed out in the appended claim. In the said accompanying drawing wherein are shown preferred arrangements embodying the principles of this invention and which drawing is intended solely for illustrative purposes:

Figure l is a more or less diagrammatic view showing one form of arrangement for carrying out the principles of the present invention;

Figures 2, 3 and 4 are similar views showing modified arrangements;

Figure 5 is a still further modified arrangement for regeneratively amplifying the output of a photo-electric cell circuit;

Figure 6 is a modified arrangement illustrating the use of a single microphone;

Figure 7 is a view comparing the sound records as obtained by the usual method with that obtained in accordance with the present invention; and

Figure 8 shows graphs comparing a sound record as produced by the present invention with one as produced by the usual method employing a constant source of light.

Referring now to the drawing and more particularly to Figure 1 thereof wherein is shown one of the preferred arrangements for attaining the objects of this invention, it will be observed that an opaque housing I0 is provided within the interior of which is located a light source II of constant intensity. The light rays emanating from this constant source of light II project through a suitable opening I2 provided in the housing I 0. Also located within the interior of the opaque housing II] is an actinic lamp I3 or other light source the light intensity of which is variable depending upon the energy supplied thereto and the purpose of which will be explained more fully hereinafter.

Arranged in advance of the housing I {I is a sound transmitter having a diaphragm I4 to which is suitably secured a mirror I5. The light rays emanating from the source of light II impinge upon this mirror I5 and are reflected therefrom to a traveling photographic film I6. Arranged immediately adjacent the primary transmitter is a secondary transmitter having a diaphragm I1 to which is secured a mirror I8. This secondary mirror I8 serves to reflect light rays from a constant source of light I9 upon a photoelectric cell 20. This photo-electric cell, which may be energized by any suitable source of supply, as the battery 2I, is included in an amplifying circuit 22 whereby to produce amplified current variations for energizing the variable intensity light source I3.

It will be understood of course that the current in the photo-electric cellcircuit will vary in accordance with the variations in the sounds as originally produced and to which the secondary diaphragm I1 is subjected. It will thus be apparent that the intensity of the light rays emanating from the variable source of light I3 will be increased or decreased in accordance with an increase or decrease in the intensity of the sounds as originally produced. These light rays of variable intensities which emanate from the light source I 3 supplement the light rays emanating from the constant source of light II with the result that the light rays which are projected against the primary mirror I5 vary in intensity in accordance with the variations of the originally produced sounds. The vibrations produced in the primary diaphragm by the sounds being recorded cause a corresponding vibration of the primary mirror I5 in consequence of which a sound record of varying amplitude is obtained on the traveling photographic film I6. At the same time, the vibrations produced in the secondary diaphragm I1 produce light rays of variable intensity which are reflected from the primary mirror I5 upon the photograph film I6, the arrangement being such that a photographic film sound record is obtained wherein the density of the record increases or decreases accordingly as the amplitude thereof increases or decreases.

Such a record is more or less diagrammatically shown in Figure 7 showing two photographic film sound records a and b. The record a is then produced by using only a constant source of light and a vibrating mirror, it being observed that in this record a while the amplitude thereof varies the density is always the same.

In contra-distinction to this record a, it will be observed that the record b varies in density accordingly as its amplitude varies, the density being increased accordingly as the amplitude thereof increases.

It will be understood that in the arrangement shown in Figure 1 as well as in the arrangements to be hereinafter described, the constant source of light II may be entirely omitted, leaving only the variable source of light I3 for producing light rays for reflection from the primary mirror I5. The arrangement shown in Figure 2 difiers from that shown in Figure 1 only in the means for variably influencing the photo-electric cell20. In this arrangement of Figure 2, it will be observed that the primary and secondary diaphragms I4 and I1 are employed as in the case of Figure 1. However, instead of securing a mirror to the secondary diaphragm, a pivotally mounted shutter 22 is provided. This shutter 22 is normally arranged to cover an opening 23 provided in the photo-electric cell housing 24, the shutter being actuated by the secondary diaphragm I1 to more or less expose the opening 23 whereby to permit a greater or less quantity of light from the source I9 to influence the photo-electric cell 20. In all other respects the arrangement of Figure 2 operates exactly as does a the arrangement of Figure 1.

In the arrangement shown in Figure 3, a single diaphram 25 is employed in place of the heretofore described primary and secondary diaphrams I4 and I1. gle diaphram 25 is a mirror 26 and a shutter 21. Vibration of the diaphram 25 causes corresponding vibration of this mirror 26 and the shutter 21. The mirror 26 of course directs the light rays emanating from within the housing I0 against the traveling photographic film, while the shutter 21 is operable to permit more or less light from the source I9 to influence the photoelectric cell 20.

In the arrangement shown in Figure 4, the primary diaphragm I4 and the primary mirror I5 are employed for producing a record on the photographic film I6 of varying amplitude. Instead of employing a secondary diaphragm as in the arrangements of Figures 1 and 2, a microphone 28 is employed. By the use of this microphone 28 the necessity for employing the photo-electric cell of Figures 1, 2 and 3 is obviated. It will be understood that the initially produced sound vibrations are converted by the microphone into corresponding electrical variations which are amplified as in the previous arrangements for suitably energizing the light source I3 for producing light rays of varying intensity. It will be understood of course that it may be preferable to combine the microphone 28 and the diaphragm I4 of Figure 4 to form a single unit. In other Words, instead of employing a separate vibrating diaphragm I4, this diaphragm may be that of the microphone, such as is illustrated in Figure 6.

Figure 5 shows still another arrangement for producing a photographic film sound record both the density and amplitude of which vary in accordance with the intensity of the sounds as originally produced. In this arrangement, the diaphragm I 4, the mirror I5, and the microphone 28 are again employed as in the arrangement of Figure 4. The electrical current variations as produced by the microphone 28 are amplified and Suitably secured to this sinthe current so amplified is employed to energize an actinic lamp 29 or other light source the light intensity of which varies in accordance with the current variation. It will be understood that this actinic lamp 29 produces light rays which vary in intensity in accordance with the variations of the originally produced sound vibrations.

As appears quite clearly in Figure 5 the actinic lamp 29 is enclosed within a housing 30 of any suitable design. Also located within the interior of this housing 30 and adapted to be influenced by the light rays emanating from the actinic lamp 29 is a photo-electric cell 3|. It will be understood that the light rays emanating from the lamp 29 variably influence this photo-electric cell 3| whereby to produce current variations in the photo-electric cell circuit 32, this current being suitably amplified and employed to energize the variable light source l3 in the housing In.

In addition to the actinic lamp 29 and the photo-electric cell 3|, the housing 3!] contains in the interior thereof one or more additional sources of light 33, the energy for which is supplied by the photo-electric cell circuit 32. These auxiliary sources of light also produce light rays which vary in intensity in accordance with the intensity of the sounds as originally produced and are relatively so arranged as to further influence the photo-electric cell 3| to still further decrease the resistance thereof with a resultant increase in the current in the circuit 32. It will thus be apparent that the arrangement as just described regeneratively amplifies the output of the photoelectric cell 3l by feeding light back upon the cell, the fed back light being produced by a portion of the energy established in the photo-electric cell circuit. It Will be understood that the light emanating from the lamp 33 is additive to the light emanating from the principal lamp 29 in consequence of which the photo-electric cell 3| is so influenced that its resistance is reduced to an irreduceable minimum, thereby producing a greatly amplified output current from the photoelectric cell circuit 32. It will be understood of course that this arrangement for regeneratively amplifying the output of the photo-electric cell may be incorporated in either of the arrangements shown in Figures 1, 2 or 3. In order to produce a more uniform distribution of light within the casing I0 and toobviate any shadow effects which may be produced by either of the lamps l l or l3, it may be preferable to employ a translucent lens 34 located between the lamp 1 l and the opening I2 provided in the casing l0, this being shown most clearly in Figure 5. At this point attention is directed to the fact that the lens 34 may of course be employed in any one of the arrangements hereinbefore described.

Figure 6 shows still another arrangement for variably influencing the photo-electric cell it such as is used in Figures 1, 2 and 3. In this modified arrangement a microphone 35 is employed to the vibrating diaphragm of which is secured a mirror 36. The mirror 36 is of course employed to reflect light emanating from within the casing H] to the traveling photographic film l6. However, instead of employing a secondary diaphragm and mirror as in Figure 1, or a second diaphragm and shutter as in Figure 2, or a shutter actuated by a vibrating diaphragm as in Figure 3, in the arrangement shown in Figure 6 a shutter 31 is employed which is actuated by means of a solenoid 38. This solenoid is variably energized by the microphone 35 in such manner that the shutter 31 is operable to expose more or less of the opening 23 in the photo-electric cell circuit in accordance with the intensity of the sounds as originally produced.

Figure 8 graphically compares the results obtained by employing a variable source of light with those obtained when a constant source of light is employed. When a constant source of light is employed as in the usual arrangement for photographically recording sound, a curve such as C would be obtained, it being observed that for a given light intensity the density of the record is the same although the sound intensity varies from the finest pianissimo sound to the strongest fortissimo sound. On the other hand, where a variable light source is employed in accordance with the principles of the present invention, a graph D would be obtained, it being observed that the density of the sound record varies in accordance with the sound intensity. In other words, when either of the hereinbefore described arrangements is employed for recording sound, a photographic sound record is obtained having very little density for the finest pianissimo sound and much density for the strongest fortissimo sound. It will be understood of course that in those instances where the constant source of light l l is employed, the intensity of the light rays emanating therefrom would be limited to a value suflicient to produce a sound record the density of which is in accordance with the finest or Weakest pianissimo sound. Any increase in the intensity of the sounds as originally produced would be represented on the record by an increased density produced by the increased intensity of the light rays emanating from the variable source i3.

The advantages of the present invention will be quite apparent to those skilled in the art inasmuch as it makes possible the recordation of sound effects upon a photographic film by means of a record which takes into account not only diirerences in the intensities of the sounds but also differences in their amplitude. It follows that the character and expressive emphasis of the reproduced composition approaches more nearly the composition as originally rendered. It will be understood, of course, that various changes may be made from time to time in the invention described herein without departing from the spirit or principles thereof and accordingly it is intended to claim the same broadly, as well as specifically, as indicated in the appended claim.

What is claimed as new and useful is:-

An apparatus for photographically recording sounds upon a photographic film including a sound responsive device, a constant intensity light source, and sound responsive means operative independently of said sound responsive device for varying the intensity of an auxiliary variable intensity light source, the latter being so operatively associated with said constant intensity light source as to produce a single beam of light the intensity of which varies in accordance with the variations in the sound waves influencing said sound responsive device, and means operatively associated with said sound responsive device for efiecting the vibration of said single beam of light in accordance with the variations in the sound waves as originally produced.

BERNARD KWAR IIN 

